Wireless Glossary and Dictionary [A-B]

A2DP: Advanced Audio Distribution Profile
The Advanced Audio Distribution Profile (A2DP) in Bluetooth specifies the protocols and procedures that define the distribution of high quality audio content, in either mono or stereo on Asynchronous Connectionless Link (ACL) channels.

AAS: Adaptive Antenna System
Adaptive Antenna System (AAS), also called Advanced Antenna System, is a technology to enable the network operators to increase the wireless network capacity. In addition, adaptive antenna systems offer the potential of increased spectrum efficiency, extended range of coverage and higher rate of frequency reuse. Adaptive antenna systems consist of multiple antenna elements at the transmitting and/or receiving side of the communication link, whose signals are processed adaptively in order to exploit the spatial dimension of the mobile radio channel. Depending on whether the processing is performed at the transmitter, receiver, or both ends of the communication link, the adaptive antenna technique is defined as multiple-input single-output (MISO), single-input multiple-output (SIMO), or multiple-input multiple-output (MIMO).

A-Band cellular
In the U.S. cellular service industry, A-Band cellular is the alternative carrier to the regional Bell operating company's cellular subsidiaryAbsolute GrantAbsolute Grant (AG), a term used in the mobile wireless channel definition, means the absolute value of the power offset permitted for the power usage.

Absorption Spectrum
Absorption Spectrum is a diagram which shows the wavelengths of electromagnetic radiation absorbed by a material. The material could be a gas, a solute or a solid. An absorption spectrum is, in a sense, the inverse of an emission spectrum.

A-Key
A-key is a secret number issued to a cellular phone that is used in conjunction with a subscriber's shared secret data information for authentication.

AC: Authentication Center (or AUC)
The Authentication Centre (AC or AUC) is a function to authenticate each SIM card that attempts to connect to the GSM core network (typically when the phone is powered on). Once the authentication is successful, the HLR is allowed to manage the SIM and services described above. An encryption key is also generated that is subsequently used to encrypt all wireless communications (voice, SMS, etc.) between the mobile phone and the GSM core network.

ACCH: Associated Control Channel
Associated Control Channel (ACCH) is the GSM signalling channels associated with a user's traffic channel or dedicated signalling channel. Two ACCH are defined for GSM Circuit Switched operation. These are SACCH (Slow Associated Control Channel) and FACCH (Fast Associated Control Channel). In GPRS packet operation, an ACCH is allocated in conjunction with a PDTCH (Packet Data Traffic Channel) and is termed as PACCH (Packet Associated Control Channel).

ACIR: Adjacent Channel Interference Ratio
Adjacent Channel Interference Ratio (ACIR) is the ratio of wanted power to the interference power from the adjacent channels.

ACLR: Adjacent Channel Leakage Ratio
Adjacent Channel Leakage Ratio (ACLR) is a measure of transmitter performance for WCDMA. It is defined as the ratio of the transmitted power to the power measured after a receiver filter in the adjacent RF channel. This is what was formerly called Adjacent Channel Power Ratio. ACLR is specified in the 3GPP WCDMA standard.

ACPR: Adjacent Channel Power Ratio
Adjacent Channel Power Ratio (ACPR) is a measurement of the amount of interference, or power, in the adjacent frequency channel. ACPR is usually defined as the ratio of the average power in the adjacent frequency channel (or offset) to the average power in the transmitted frequency channel. It is a critical measurement for CDMA transmitters and their components. It describes the amount of distortion generated due to nonlinearities in RF components. The ACPR measurement is not part of the cdmaOne standard.

ACS: Adjacent Channel Selectivity
Adjacent Channel Selectivity (ACS) is a measurement of a receiver's ability to process a desired signal while rejecting a strong signal in an adjacent frequency channel. ACS is defined as the ratio of the receiver filter attenuation on the assigned channel frequency to the receiver filter attenuation on the adjacent channel frequency.

ACTS: Advanced Communications Technology and Services
Advanced Communications Technology and Services (ACTS) is an organization in Europe spearheading the development of 3G technologies in Europe. ACTS succeeded RACE and is focusing on wideband multiple access techniques.

AP: Access point
Access points act as a central transmitter and receiver of WLAN radio signals. Access points used in home or small business networks are generally small, dedicated hardware devices featuring a built-in network adapter, antenna, and radio transmitter. Access points support Wi-Fi wireless communication standards.

Ad hoc
Ad hoc, also known as Ad hoc mode, refers to a short-term wireless network framework created between two or more wireless network adapters without going through an access point. In other words, an Ad hoc network allows computers to "talk" (send data) directly to and from one another. Ad hoc networks are handy for quickly trading files when you have no other way of connecting two or more computers. For an ad hoc network to work, each computer on the network needs a wireless network card installed, and you must set your wireless network cards (installed in each computer on the network) to Ad Hoc mode.

Ad hoc mode
Ad hoc mode refers to a wireless network in which devices can communicate directly with one another without using an AP or a connection to a regular network.

Ad hoc network
Ad hoc network refers to a short-term wireless network framework created between two or more wireless network adapters without going through an access point. Ad hoc networks are handy for quickly trading files when you have no other way of connecting two or more computers.

Adaptive array antennas
Adaptive array antenna is a type of advanced smart antenna technology that continually monitors a received signal and dynamically adapts signal patterns to optimize wireless system performance. The arrays use signal processing algorithms to adapt to user movement, changes in the radio-frequency environment and multi-path and co-channel interference.

Adaptive Equalizer
Adaptive Equalizer is a channel equalizer whose parameters are updated automatically and adaptively during the transmission of data. These equalizers are commonly used in fading channels to improve transmission performance.

Adaptive power control
Adaptive power control is a technique employed by wireless infrastructure systems that lowers the power of a signal in a cell site whenever the site detects that the user's phone is close to the source of the signal. This saves power in the phone, and thus saving battery life too.

ADC: Analog-to-Digital Converter
Analog-to-Digital Converter (ADC, A/D or A to D) is an electronic device that converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC). ADC can uniquely represents all analog input values within a specified total input range by a limited number of digital output codes.

Adjacent Channel
Adjacent Channel is a channel or frequency that is directly above or below a specific channel or frequency. First-adjacent is immediately next to another channel, and second-adjacent is two channels away, and so forth. Information on adjacent channels is used in keeping stations from interfering with one another.

Adjacent channel interference
Adjacent channel interference refers to signal impairment to one frequency due to presence of another signal on a nearby frequency.

ADPCM: Adaptive Differential Pulse Code Modulation
Adaptive Differential Pulse Code Modulation(ADPCM) is the process by which analog voice samples are encoded into high-quality digital signals. The first ADPCM standardized by the CCITT is G.721 for 32 kbps. Later came the standards G.726 and G.727 for 40, 32, 24 and 16 kbps. ADPCM is used to send sound on fiber-optic long-distance lines as well as to store sound along with text, images, and code on a CD-ROM.

AGC: Automatic Gain Control
Automatic Gain Control (AGC) is a system which holds the gain and, accordingly, the output of a receiver substantially constant in spite of input-signal amplitude fluctuations.

AGCH: Access Grant Channel
Access Grant Channel(AGCH) is a downlink control channel used in GSM systems to assign mobiles to a Stand-alone Dedicated Control Channel (SDCCH) for initial assignment.

AGPS: Assisted Global Positioning System
Assisted Global Positioning System (AGPS) is a method used for determining mobile station (MS) location in terms of universal latitude and longitude coordinates. This capability has been mandated for wireless carriers in the United States by the Federal Communication Commission, so emergency callers can be easily located in times of crisis. AGPS implies that the mobile not only has GPS hardware and software but that the wireless network is providing the mobile with short assistance messages.

Air Interface
In wireless communications, the air interface is the radio frequency (RF) part of the network that transmits signals between base stations and end-user equipment. The air interface is defined by specifications for a specific format such as GSM, cdma2000, GPRS, or W-CDMA.

AirPort
AirPort is the Apple's marketing name for its 802.11b wireless networking technology. AirPort, based on IEEE 802.11b, is a local area wireless networking system from Apple Computer and certified as compatible with other 802.11b devices. A later family of products based on the IEEE 802.11g specification is known as AirPort Extreme, offering speeds of up to 54 megabits per second and interoperability with older products.

Airtime
Airtime is the time elapsed between the start of a call achieved by connecting to your service provider's network and the termination of a call achieved by pressing the end button. Network connection time includes signals received prior to voice transmission, such as busy signals and ringing.

A-Key
A-key is a secret number issued to a cellular phone that is used in conjunction with a subscriber's shared secret data information for authentication.

Aliasing
Aliasing is a type of signal distortion that occurs when sampling frequency of a signal is less than the Nyquist rate.

ALOHA
ALOHA is a packet-based radio access protocol developed by the University of Hawaii where every packet sent is acknowledged. Lack of an acknowledgement is an indication of a collision and results in a retransmission.

AM: Amplitude Modulation
Amplitude Modulation (AM) uses amplitude variation in proportion to the amplitude of the modulating signal, and is usually taken as DSB-LC for commercial broadcast transmissions and DSB-SC for multiplexed systems.

AMC: Adaptive Modulation and Coding
Adaptive Modulation and Coding (AMC) is an alternative link adaptation method in 3G mobile wireless communication. AMC provides the flexibility to match the modulation-coding scheme to the average channel conditions for each user. With AMC, the power of the transmitted signal is held constant over a frame interval, and the modulation and coding format is changed to match the current received signal quality or channel conditions.

A-MIMO: Adaptive Multiple Input Multiple Output
Adaptive Multiple Input Multiple Output (A-MIMO or Adaptive MIMO) is a scheme to enhance the MIMO technology by employing adaptive coding and modulation techniques for the purpose of improving channel capacity, diversity, and robustness of wireless communications. In an adaptive MIMO system, the system parameters are jointly optimized to adapt to the changing channel conditions through link adaptation techniques that can track the time-varying characteristics of the wireless channel. The goal is to maximize the resources available in multiple antenna channels by using optimal schemes at all times.

Amplifier
Amplifier, or electronic amplifier, is commonly used in radio and television transmitters and receivers, high-fidelity ("hi-fi") stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers.

AMPS: Advanced Mobile Phone System Service
Advanced Mobile Phone System (AMPS) Service is the analog mobile phone system standard, introduced in the Americas during the early 1980s. Though analog is no longer considered advanced at all, the relatively seamless cellular switching technology AMPS introduced was what made the original mobile radiotelephone practical, and was considered quite advanced at the time.

AMR: Advanced Multi Rate Codec
Advanced Multi Rate Codec (AMR) is a speech codec standardized by ETSI for GSM. The codec adapts its bit-rate allocation between speech and channel coding, thereby optimizing speech quality in various radio channel conditions. For this reason, 3GPP (under which the next stage GSM speech quality will be realized) has selected the AMR codec as an essential speech codec for the next generation system.

AMS: Adaptive MIMO Switching
Adaptive MIMO Switching (AMS) is a scheme to switch between multiple MIMO modes to maximize spectral efficiency with no reduction in coverage area. In an adaptive MIMO switching system, the system parameters are jointly optimized to adapt to the changing channel conditions through link adaptation techniques that can track the time-varying characteristics of the wireless channel. The goal is to maximize the resources available in multiple antenna channels by using optimal schemes at all times.

AMTA: American Mobile Telecommunications Association
American Mobile Telecommunications Association (AMTA) is a trade group, based in Washington, D.C., representing specialized mobile radio operators.

Analog System
Analog system uses an analog transmission method to send voice, video and data-using analog signals, such as electricity or sound waves, that are continuously variable rather than discreet units as in digital transmissions. Mobile analog systems include AMPS, NMT and ETACS.

Angle diversity
Angle diversity is a technique using multiple antenna beams to receive multipath signals arriving at different angles.

Antenna
Antenna is a device which radiates and/or receives radio signals.

Antenna beamwidth
Antenna beamwidth, also known as the half-power beamwidth, is the angle of an antenna pattern or beam over which the relative power is at or above 50% of the peak power.

Antenna directivity
Antenna directivity, also known as antenna gain, is the relative gain of the main beam of an antenna pattern to a reference antenna, usually an isotropic or standard dipole.

Antenna gain
Antenna gain, also known as antenna directivity, is the relative gain of the main beam of an antenna pattern to a reference antenna, usually an isotropic or standard dipole.

APC: Automatic Power Control
Automatic Power Control (APC) is a technique of measuring the performance of a radio channel and adjusting the power of the transmitter to a level appropriate for link characteristics.

APCM: Adaptive Pulse Code Modulation
Adaptive Pulse Code Modulation (APCM) is a technique used to share occupied bandwidth among a maximum number of subscribers during peak times by reducing the signal sampling rates of each subscriber.

APS: Application Support
Application Support (APS) is a sublayer in the ZigBee protocol stack. The responsibilities of the APS sub-layer include maintaining tables for binding to match two devices together based on their services and their needs, and forwarding messages between bound devices. The APS sub-layer is also responsible to determine the responsibilities of the ZDO, to initiate/respond to binding requests, and to establish a secure relationship between network devices.

ARCH: Access Response Channel
Access Response Channel (ARCH), a logic sub-channel of SPACH specified in IS-136, carries wireless system responces from the cell site to the user equipment.

ARIB: Association of Radio Industries and Businesses
Association of Radio Industries and Businesses (ARIB) is the Japanese standards-setting organization.

ARDIS: Advanced Radio Data Information Service
Advanced Radio Data Information Service (ARDIS) is a wireless two-way data network jointly owned and operated by Motorola and IBM.

ARFCN: Absolute Radio Frequency Channel Numbers
Absolute Radio Frequency Channel Numbers (ARFCN) is a channel numbering scheme used to identify specific RF channels in a GSM radio system.

ARQ: Automatic Repeat Request
Automatic Repeat Request (ARQ) is a communication protocol in which the receiving device detects errors and requests retransmissions. When the receiver detects an error in a packet, it automatically requests the transmitter to resend the packet. This process is repeated until the packet is error free or the error continues beyond a predetermined number of transmissions. ARQ is sometimes used with Global System for Mobile (GSM) communication to guarantee data integrity.

Attenuation
Attenuation refers to decreasing in signal magnitude between two points. These points may be along a radio path, transmission line or other devices.

Attenuator
Attenuator is a device specifically designed to decrease the magnitude of a signal transmitted through it.

AUC: Authentication Center
The Authentication Center (AUC) is a device, usually located in the HLR of a GSM system, to authenticate each SIM card that attempts to connect to the GSM core network (typically when the phone is powered on). Once the authentication is successful, the HLR is allowed to manage the SIM and services described above. An encryption key is also generated that is subsequently used to encrypt all wireless communications (voice, SMS, etc.) between the mobile phone and the GSM core network.

Average power
Average power is the peak power averaged over time and is usually applied to pulsed systems where the carrier power is switched on and off.

AWGN: Additive White Gaussian Noise
Additive White Gaussian Noise (AWGN) is the statistically random radio noise characterized by a wide frequency range with regards to a signal in a communications channel.

Backhaul
In wireless technology, backhaul refers to transporting voice and data traffic from a cell site to the switch.

Backscattering
Backscattering is radio wave propagation in which the direction of the incident and scattered waves, resolved along a reference direction (usually horizontal) are oppositely directed. A signal received by backscattering is often referred to as "backscatter."

Band
Band in telecommunication refers to the following definitions: 1. The range of frequencies between two defined limits which are used for a specific purpose. 2. One of the geopolitical boundaries established to define a WATS (wide-area telephone service) serving area.

Band Elimination Filter
Band Elimination Filter is an electrical device which blinds a receiving unit from recognizing a specific range of frequencies.

Band Pass Filter
Band Pass Filter is a radio wave filter with a specific range of frequencies in which it is designed to pass, while rejects frequencies outside the pass-band. Resistor-inductor-capacitor circuit is an example of Band Pass Filter.

Bandwidth
Bandwidth is the portion of the frequency spectrum required to transmit desired information. Each radio channel has a center frequency and additional frequencies above and below this carrier frequency which is used to carry the transmitted information. The range of frequencies from the lowest to the highest used is called the bandwidth.

Baseband
Baseband is the transmission of a digital or analog signal signaling at its original frequencies and in its original form. It should not be changed by modulation.

Baseband layer
Baseband layer, also known as baseband packet, is a physical layer protocol in the Bluetooth protocol stack. The Baseband in the Bluetooth manages physical channels and links apart from other services like error correction, data whitening, hop selection and Bluetooth security. The Baseband layer lies on top of the Bluetooth radio layer in the bluetooth stack. The baseband protocol is implemented as a Link Controller, which works with the link manager for carrying out link level routines like link connection and power control. The baseband also manages asynchronous and synchronous links, handles packets and does paging and inquiry to access and inquire Bluetooth devices in the area.

Baseband signal
Baseband signal is a signal with frequency content centered around DC. Typically it is the modulating signal for an RF carrier.

B-Band cellular
In the U.S. cellular service industry, B-Band cellular refers to the regional Bell operating company's cellular subsidiary.

BCCH: Broadcast Control Channel
Broadcast Control Channel (BCCH) is a downlink-point-to-multipoint logical channel in GSM and cdma2000 systems used to send identification and organization information about common control channels and cell services.

B-CDMA: broadband code division multiple access
Broadband code division multiple access (B-CDMA) is designed to correct many of the inherent short-falls of IS-95 (narrowband CDMA) and other digital narrowband technologies. In addition, it is being designed as a long-term solution to both voice and data wireless needs -- fixed and mobile. Some of the technical aspects of the B-CDMA air interface are related to its propagation characteristics.

BCH code:Bose-Chaudhuri-Hocquenghem Code
Bose-Chaudhuri-Hocquenghem (BCH) Code is a family of powerful cyclic block forward error correction codes used in the transmission of data.

BCH: Broadcast Channels
Broadcast Channels (BCH) are a group downlink point to multipoint logical channels used by mobiles to synchronize to and receive information necessary to access a cell in GSM, cdma2000, and WCDMA systems.

Bent pipe technology
Bent pipe technology is a satellite technology to transmit calls from one point on Earth to a satellite and back down to another point.

BE Service: Best Effort Service
Best Effort (BE) Service is one of the five QOS service types defined in the IEEE 802.16 WiMAX. The 802.16 protocol supports five types of QoS: UGS (Unsolicited grant service), rtPS (Real time polling Service), ertPS (Extended Real-time POLLING SERVICE), nrtPS (Non-real-time polling service and BE (Best effort service). The aim of the Best Effort (BE) service is to provide efficient service to best effort traffic.

BGCF: Breakout Gateway Control Function
Breakout Gateway Control Function (BGCF), a component in the IP Multimedia Subsystem (IMS), controls call transfers to and from the public switched telephone network (PSTN).

Big LEO
Big LEO refers to a low-earth orbit satellite system that will offer voice and data services, e.g., Iridium, Globalstar. Orbits, typically a few thousand kilometers high, that are intermediate in size between little LEO (low Earth orbit) and geosynchronous orbits. The term is applied especially to some of the latest generation of communication satellites that support communications using small handheld sets.

BlackBerry
BlackBerry is a two-way wireless device, made by Waterloo, that allows users to check e-mail and voice mail (translated into text), as well as to page other users via a wireless network service. Also known as a RIM device, it has a miniature qwerty keyboard for users to type their messages. It uses the SMS protocol. BlackBerry users must subscribe to a wireless service that allows for data transmission.

BLER: Block Error Rate
Block Error Rate (BLER) is a ratio of the number of erroneous blocks to the total number of blocks received on a digital circuit. Block error rate (BLER) is used for W-CDMA performance requirements tests (demodulation tests in multipath conditions, etc). BLER is measured after channel de-interleaving and decoding by evaluating the Cyclic Redundancy Check (CRC) on each transport block.

Block code
Block code is a family of codes having a one-to-one mapping between k-symbol source words and n-symbol code words.

Blocking probability
Blocking probability is the statistical probability that a telephone connection cannot be established due to insufficient transmission resources in the network. Usually expressed as a percentage or decimal equivalent of calls blocked by network congestion during the busy hour.

bluesnarf (bluesnarfing)
Bluesnarfing is the theft of information from a wireless device through a Bluetooth connection.

Bluetooth
Bluetooth, defined in IEEE 802.15, is for wireless personal area networks (WPANs), which has characters such as short-range, low power, low cost, small networks and communication of devices within a Personal Operating Space. Bluetooth is for wireless transmission between a wide variety of devices such as PCs, cordless phone, headsets and PDAs within 10-meter range.

BPSK: Binary Phase Shift Keying
Binary Phase Shift Keying (BPSK) is a type of phase modulation using 2 distinct carrier phases to signal ones and zeros. BPSK is the simplest form of PSK. It uses two phases which are separated by 180A° and so can also be termed 2-PSK. It does not particularly matter exactly where the constellation points are positioned, and, in this figure, they are shown on the real axis, at 0A° and 180A°. This modulation is the most robust of all the PSKs since it takes serious distortion to make the demodulator reach an incorrect decision. It is, however, only able to modulate at 1bit/symbol (as seen in the figure) and so is unsuitable for high data-rate applications.

BREW: Binary Runtime Environment for Wireless
Binary Runtime Environment for Wireless (BREW) is an open system created by Qualcomm for delivering over-the-air applications and data. The hottest use for BREW to date has been downloadable games

Broadband
Broadband refers to telecommunication that provides multiple channels of data over a single communications medium, typically using some form of frequency or wave division multiplexing.

Broadband PCS
Broadband PCS is the personal communications services created in the A- through F-Block auctions and used for voice and data. Mobile broadband PCS services include both voice and advanced two-way data capabilities that are generally available on small, mobile multifunction devices.

Broadband Wireless Access
Broadband wireless access is a technology aimed at providing wireless access to data networks, with high data rates. According to 802.16-2004 standard, broadband means "having instantaneous bandwidth greater than around 1 MHz and supporting data rates greater than about 1.5 Mbit/s". From the point of view of connectivity, broadband wireless access is equivalent to broadband wired access, such as ADSL or cable modems. It is planned to be used in the next few years and is thought to be used up to 40 miles away.

BS: Base Station
Base station (BS), also called cell site, is the local cellular tower and radio antenna (including the radios, controller, switch interconnect, etc.) that handles communication with mobile users in a particular area or cell. A cellular network is made up of many cell sites or base stations, all connected back to the switch via landline or microwave.

BSC: Base Station Controller
Base Station Controller (BSC) is a device and software associated with a base station that permits it to register mobile phones in the cell, assign control and traffic channels, perform handoff and process call setup and termination.

BSIC: Base Station Identity Code
Base Station Identity Code (BSIC) is a unique code contained in messages on the broadcast channels of a cell or base station that uniquely identifies the base station.

BSS: Base Station Subsystem
The Base Station Subsystem (BSS) is the section of a GSM network which is responsible for handling traffic and signalling between a mobile phone and the Network Switching Subsystem. The BSS carries out transcoding of speech channels, allocation of radio channels to mobile phones, paging, quality management of transmission and reception over the Air Interface and many other tasks related to the radio network.

BSSID: Basic Service Set Identifier
BSSID refers to the MAC address of the Station (STA) in an Access Point (AP) in an infrastructure mode BSS defined by the IEEE 802.11-1999 Wireless Lan specification. This field uniquely identifies each BSS. In an IBSS, the BSSID is a locally administered IEEE MAC address generated from a 46-bit random number. The individual/group bit of the address is set to 0. The universal/local bit of the address is set to 1.

BT: Bandwidth Time Product
Bandwidth Time Product (BT) is the result obtained by multiplying the system bandwidth by the signal duration. As a general rule, the system bandwidth must be approximately equal to the reciprocal of the signal duration to produce an output signal of the same general form as the input, i.e., BT»1.

BTA: Basic Trading Area
Basic Trading Area (BTA) refers to the area or "footprint" in which an entity is licensed to transmit their frequencies. BTAs were established by Rand McNally and are defined as county lines. Rand McNally licensed their mapping data to the FCC for ease of designation for site licenses. BTAs are about the size of a cellular MSA and cross state lines in some instances. BTAs are grouped into larger areas called MTAs.

BTC: Block Turbo Code
Block Turbo Code (BTC) is a type of turbo codes. BTC is a product code obtained from the concatenation of either two extended or two expurgated Bose-Chaudhuri-Hocquenghem (BCH) codes. Block Turbo-codes (BTC) are promising forward error correction (FEC) codes providing close-to-optimal coding gain for rather high coding rate (R > 0.7) and less subject to an error floor than Convolution Turbo Codes (CTC).

BTS: Base Transceiver Station
Base Transceiver Station (BTS) effects radio communications with mobile stations (MS) via its respective radio access system and transmits/receives signals to/from connected radio network controllers (RNC) located along transmission routes.